I'm flying from Costa Rica to Chile in November with a B737-800 plane. I'm wondering if this is a different aircraft than the B737 Max 8 or if it's the same?
All B737 Max, as of today 19-Sept-2019, are still grounded and will be for the foreseeable future. So if you are flying in an aircraft, you are guaranteed that it will not be one of those.
As for the underlying question "is it safe to fly in airplane model "X"?" the answer always is that if authorities are allowing it to fly, it is safe to the best of our knowledge.
Yes, it is a different generation of the 737.
The Boeing 737 currently exists in its 4th generation:
- Original Series: The first generation first flew in 1967 and consists of the 737-100 and 737-200 models, which differ in fuselage length.
- Classic Series: The Classic first flew in 1984 and the main difference is the use of high bypass turbofan engines. It consists of 3 different length variants: 737-300/-400/-500.
- Next Generation (NG) Series: The NG first flew in 1997 and consists of 4 different length variants: 737-600/-700/-800/-900. The aircraft you will fly on is from this series, as are most 737s, which are still in use today.
- MAX Series: The MAX first flew in 2016 and also consists of 4 different length variants: 737 MAX 7, MAX 8, MAX 9 and MAX 10. As Federico said, all variants of this series are currently grounded because of problems with the newly introduced MCAS.